The present invention relates to a dual carcass flexible hose of the type comprising a first carcass for conveying fluid and a secondary carcass surrounding the first carcass in such a way as to define a space for the retention of the fluid and in which the first and secondary carcasses are connected, at each end, to a flanged metal tubular connector.
Flexible hoses of the above-mentioned type are widely utilised for the transport of fluids such as oil-rich fluids, the escape of which would constitute a serious risk for the environment and public health, whenever the hose is subjected, during use, to significant forces of flexure and in general to particularly severe manipulation conditions.
Prior art flexible hoses of the above-mentioned type are normally provided with leak detector devices operable to indicate an escape of the conveyed fluid from the first carcass and its ingress into the secondary carcass which functions as retainer; even if the secondary carcass is made in such a way as to withstand the pressure of the fluid being conveyed, the emission of an alarm signal by means of a leak detector is essential to make it possible to act promptly to replace the damaged hose before a failure occurs leading to consequent escape of fluid from the secondary carcass.
Known devices for the detection of leakages use the radial expansion of the secondary carcass or the increase of pressure in the secondary carcass which occurs upon loss of fluid from the first carcass, in order to provide a detectable signal.